1. Field of the Invention:
The present invention relates to the use of a spin trap in a cosmetic and/or dermatological composition, for the light-protective, anti-ageing and/or anti-ache treatment of the skin, including the scalp. The invention also relates to a process for the topical cosmetic treatment of the skin and to a cosmetic and/or dermatological composition containing this spin trap.
2. Discussion of the Background:
In order to provide an effective protection for the skin against sunlight, to reduce the effects of age and to eliminate the imperfections of the skin caused by acne, it is currently necessary to use several antioxidant active agents; at present, effective care of the skin against these effects and imperfections is obtained by incorporating 4 to 8 antioxidant active agents. However, the introduction of a large number of active agents into a cosmetic and/or dermatological composition complicates its manufacture, resulting particularly in an increase in the cost price thereof.
Consequently, the subject of the invention is a cosmetic and/or dermatological composition and the use thereof for the light-protective, anti-ageing and/or anti-acne treatment of the skin which enables these drawbacks to be overcome.
Spin traps and more especially nitroxide free radicals are generally used in spectroscopy as a probe for electron paramagnetic resonance (EPR), as described in the document "Electron paramagnetic resonance (EPR) imaging in skin: Biophysical and biochemical microscopy" by J. Fuchs et al., vol. 98, No. 5, 1992 p. 713 to 719 or U.S. Pat. No. 4,849,346. The measuring is based on the reduction of the spin traps.
Nitroxide free radicals are also used for displaying human organs by magnetic resonance study. More precisely, the subject of the invention is a use for the light-protective, anti-ageing and/or anti-acne treatment of the skin, of a spin trap employed as an electron paramagnetic resonance measurement probe, in a cosmetic or dermatological composition.
It has already been envisaged to inject a solution of N-tert-butyl-.alpha.-phenylnitrone into rodents for the purpose of lowering the level of oxidized proteins and of increasing the activity of glutamine synthetase and of neutral protease in their brains: see in this respect the document "Reversal of age-related increase in enzyme activity, and loss in temporal and spatial memory by chronic administration of the spin-trapping compound N-tert-butyl-.alpha.-phenylnitrone" by J. M. Carney et al., Proc. Natl. Acad. Sci. vol. 88, pp. 3633-3636, May 1991; however, this document does not in any way contemplate the use of this nitrone in a cosmetic and/or dermatological composition for an anti-ageing, anti-acne and/or light-protective treatment of the skin.
Moreover, it is known from document EP-A-0,327,263 to apply a composition containing a free-radical precursor and an adjuvant such as a reducing agent, an antioxidant or a hydroxyl-radical-sequestering agent to the scalp in order to stimulate hair growth. However, this document does not in any way teach the use of this free-radical precursor for the light-protective, anti-ageing and/or anti-acne treatment of the skin.